I. Field of the Invention
This invention relates generally to a coupling pin used to secure a wheeler trailed vehicle to a wheeler tractor vehicle. A representative use is coupling an agricultural tractor and a trailed vehicle with a drawbar and tongue respectively to tow the trailed vehicle with the tractor.
II. Description of the Prior Art
There are a number of coupling devices made to attach a trailed vehicle to a tractor. In Chapman et al U.S. Pat. No. 2,900,864 a horizontal grooved latch pin is secured by a chain using an arrow-shaped opening on a latch plate to fit over a matching groove in the end of the latch pin. The weight of the chain and plate is relied upon to secure the end of the chain in place and thus hold the grooved latch pin in place.
In Stastny U.S. Pat. No. 2,180,558 a hinged bound member is inserted through a matching hole in a coupling pin and a chain secured to the hinged bound member across the hole to secure the member in place to prevent removal of the coupling pin. In Ligget U.S. Pat. No. 340,333 an axle clip is secured around the coupler using slots to hold the clip in place. In Honeycutt et al U.S. Pat. No. 2,593,453 a coupling pin is secured by a pair of U-shaped frame members which partially enclose the tongue.
In Schleicher U.S. Pat. No. 466,967 a pin is secured by a chain through eyelets secured to the pin and hinge-joint. In May U.S. Pat. No. 603,196 a coupling bolt is secured by a pin which is held in place by a spring which spans the pin and is attached to one end and fits into a recess in the opposite end of the pin.
None of the previous devices provides the combination of functions of my present device, namely a method of securing a vertical coupling pin with a chain. The chain is simple to connect and must either be removed or broken to remove the coupling pin.